Real-time video encryption for H.263 videos

In this paper two H.263 video encryption algorithms have been implemented and compared. These algorithms encrypt selected sign bits of DCT coefficients using secret key cryptography algorithms such as DES, AES. The aim of selective encryption is to reduce the amount of data to encrypt while maintaining a sufficient level of security. This computation saving is very desirable especially in constrained communications (real-time networking, high-definition delivery, and mobile communications with limited computational power devices). In addition, selective encryption allows preserving some codec functionalities such as scalability. The first algorithm encrypts the sign bits of the entire video in one iteration. The second algorithm is the modification of the first which meets the requirements of real-time applications by encrypting the sign bits framewise.